Corporate users and others manage data by using storage control apparatuses. A storage control apparatus groups physical storage areas which multiple storage apparatuses comprise respectively as redundant storage areas based on RAID (Redundant Array of Independent (or Inexpensive) Disks). The storage control apparatus creates logical volumes by using grouped storage areas, and provides the same to a host computer (hereinafter referred to as the host).
The storage control apparatus, receiving a read request from the host, instructs a hard disk to read the data. The address of the data read from the hard disk is converted, stored in a cache memory, and transmitted to the host.
The hard disk, if unable to read data from storage media due to the occurrence of a certain type of problem in the storage media, a magnetic head or others, retries [read] after a period of time. If unable to read the data from the storage media in spite of performing the retry processing, the storage control apparatus performs correction copy, and generates the data required by the host. Correction copy is the method for restoring the data by reading the data and the parity from the other hard disks belonging to the same parity group as the hard disk in which the failure occurred (Patent Literature 1).